1. Field of the Invention
The present invention relates to an optical device and method of formation thereof and, more particularly, to an optical waveguide chip capable of increasing an allowable error range relative to precise coupling. In accordance with the invention, optical connection loss is barely affected when an optical waveguide chip is connected to an optical fiber, an optical fiber array module or another optical waveguide chip for packaging of an optical waveguide device.
2. Related Art
In planar waveguide technology for an optical waveguide device, one goal is to fabricate lowcost parts for optical communication through mass production. In general, the fabrication process for an optical waveguide chip has developed such that the optical waveguide chip can be mass produced based on semiconductor fabrication technology. However, compared to fabrication technology, packaging technology for an optical waveguide device has been slow to develop. Such slow development rate of the packaging technology has been the biggest hindrance to mass production. In particular, the technology of coupling an optical waveguide chip to an optical fiber, an optical fiber array module or another optical waveguide chip is very important in passive elements as a factor influencing the characteristics and cost of a device. This technology is vital for low-cost mass production, as well as for securing the optical characteristics of an optical waveguide device.
As explained in more detail below, interconnection methods for coupling an optical waveguide chip to another optical waveguide chip, an optical fiber array module or an optical fiber have the disadvantage of being required to meet stringent precision requirements in the interconnection in order to avoid excessive coupling loss. Therefore, highly skilled personnel and exorbitant time are required, with consequent increases in difficulty and cost of manufacturing or mass production.
To solve the above problems, it is an object of the present invention to provide an optical waveguide chip and method of formation thereof, wherein the optical waveguide chip is capable of increasing an allowable error range relative to precise coupling without an increase in optical connection loss when the optical waveguide chip is connected to an optical fiber, an optical fiber array module or another optical waveguide chip for packaging of an optical waveguide device.
Accordingly, to achieve the above object, there is provided an optical waveguide chip comprising an output waveguide connected to an optical fiber, an optical fiber array module or another optical waveguide chip, wherein the output waveguide has a coupling cross-section wider than the core of the optical fiber (in the first case), wider than the core of the optical fiber of the optical fiber array module (in the second case), and wider than the core of the waveguide of the other optical waveguide (in the third case).
Preferably, the cross-section width of the output waveguide of the optical waveguide chip gradually increases toward the end of the waveguide, with a slant angle of 10xc2x0 or less.